Beam steering device and system including the same

ABSTRACT

A beam steering device includes a waveguide configured to transmit a beam therethrough; a cladding layer provided on the waveguide and including a material having a refractive index that varies according to a voltage applied thereto; and an electrode layer including at least two electrodes configured to independently voltages to at least two portions of the cladding layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2016-0150335, filed on Nov. 11, 2016 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND 1. Field

Methods and apparatuses consistent with exemplary embodiments relate tobeam steering devices and systems including the same.

2. Description of the Related Art

Examples of a method of steering a laser beam to a desired positioninclude a method of mechanically rotating a portion to which a laserbeam is emitted and an optical phased array (OPA) method usinginterference between a bundle of laser beams output from a plurality ofwaveguides or a plurality of unit cells. The OPA method may steer alaser beam by electrically or thermally controlling the waveguides orthe unit cells. Since the method of mechanically rotating the portion towhich a laser beam is emitted uses a motor or a microelectromechanicalsystem (MEMS), a volume may be large and costs may be high. Since theOPA method uses the plurality of waveguides, an overall volume may belarge and an error may occur when a phase is modulated.

SUMMARY

Exemplary embodiments may provide beam steering devices having simplestructures.

Exemplary embodiments may further provide systems including beamsteering devices having simple structures.

According to an aspect of an exemplary embodiment, there is provided abeam steering device including: a waveguide configured to transmit abeam therethrough; a cladding layer provided on the waveguide andincluding a material having a refractive index that varies according toa voltage applied thereto; and an electrode layer including at least twoelectrodes configured to independently apply voltages to at least twoportions of the cladding layer.

The at least two electrodes may be electrically independent.

The cladding layer may include an electro-optic material.

The electro-optic material may include a liquid crystal, TiN,KTa_(1-x)Nb_(x)O₃ (KTN), or NbO_(x).

The cladding layer may include an oxide semiconductor.

The oxide semiconductor may include at least one from amongIndium-Tin-Oxide (ITO), Indium-Zinc-Oxide (IZO), Ga—In—Zn-Oxide (GIZO),Al—Zn-Oxide (AZO), Ga—Zn-Oxide (GZO), and ZnO.

The waveguide may include silicon or silicon nitride.

The waveguide may be configured to operate as an electrode.

The at least two electrodes of the electrode layer may include aplurality of pixel electrodes that are arranged in a matrix and areelectrically independent.

The electrode layer may include a first portion configured to apply afirst voltage to a first portion of the cladding layer and a secondportion configured to apply a second voltage to a second portion of thecladding layer.

The cladding layer may include a metal oxide semiconductor structureprovided along a surface of the electrode layer.

The cladding layer may include a first layer and a second layer, whereinthe first layer may include at least one from among Indium-Tin-Oxide(ITO), Indium-Zinc-Oxide (IZO), Ga—In—Zn-Oxide (GIZO), Al—Zn-Oxide(AZO), Ga—Zn-Oxide (GZO), and ZnO and the second layer may include anyone from among HfO₂, Al₂O₃, SiN_(x), and SiO₂.

The waveguide, the cladding layer, and the electrode layer may berepeatedly stacked two or more times.

The waveguide may be configured to operate as an active prism accordingto a change in the refractive index of the cladding layer.

According to an aspect of another exemplary embodiment, there isprovided a system including: a light source; a beam steering deviceconfigured to steer a beam incident from the light source towards anobject; and a detector configured to detect the beam steered by the beamsteering device and reflected by the object, wherein the beam steeringdevice includes: a waveguide configured to transmit the beamtherethrough; a cladding layer provided on the waveguide and including amaterial having a refractive index that varies according to a voltageapplied thereto; and an electrode layer comprising at least twoelectrodes configured to independently apply voltages to at least twoportions of the cladding layer.

The cladding layer may include an electro-optic material.

The electro-optic material may include a liquid crystal, TiN,KTa_(1-x)Nb_(x)O₃ (KTN), or NbO_(x).

The cladding layer may include an oxide semiconductor.

The at least two electrodes of the electrode layer may include aplurality of pixel electrodes that are arranged in a matrix and areelectrically independent.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of exemplary embodiments,taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a beam steering device according toan exemplary embodiment;

FIG. 2 is a plan view of FIG. 1;

FIG. 3A is a graph showing a relationship between a wavelength and aneffective refractive index of a waveguide when a laser beam passesthrough a cladding layer of the beam steering device of FIG. 1 (in a TM0mode);

FIG. 3B is a graph showing a relationship between a wavelength and aneffective refractive index of the waveguide when a laser beam passesthrough the cladding layer of the beam steering device of FIG. 1 (in aTE0 mode);

FIG. 4 is a cross-sectional view illustrating an example where a lowerelectrode layer is further provided in the beam steering device of FIG.1;

FIG. 5 is a cross-sectional view of a beam steering device according toanother exemplary embodiment;

FIG. 6 is a cross-sectional view of a beam steering device according toanother exemplary embodiment;

FIG. 7 is a plan view of FIG. 6;

FIG. 8 is a plan view for explaining refractive index change portionsdue to pixel electrodes of the beam steering device of FIG. 6;

FIG. 9 is a graph showing a relationship between an angle at which abeam is output and a gradient θ of a boundary between refractive indexchange portions of the beam steering device of FIG. 6;

FIG. 10 is a cross-sectional view of a beam steering device according toanother exemplary embodiment; and

FIG. 11 is a view of a system including a beam steering device accordingto an exemplary embodiment.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described more fully withreference to the accompanying drawings. In the drawings, the samereference numerals denote the same elements and sizes of elements may beexaggerated for clarity and convenience of explanation. It will beunderstood that, although the terms first, second, etc. may be usedherein to describe various elements, these elements should not belimited by these terms. These terms are only used to distinguish oneelement from another.

As used herein, the singular forms “a”, “an”, and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising” used herein specify the presence of statedcomponents, but do not preclude the presence or addition of one or moreother components. Sizes or thicknesses of elements in the drawings maybe exaggerated for clarity of explanation. Also, it will be understoodthat when a material layer is referred to as being “formed on” asubstrate or another layer, the material layer may be directly orindirectly formed on the substrate or the other layer. That is, forexample, intervening layers may be present. A material of each layer inthe following exemplary embodiments is exemplary and other materials maybe used.

Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list.

FIG. 1 is a cross-sectional view of a beam steering device BS accordingto an exemplary embodiment. FIG. 2 is a plan view of the beam steeringdevice BS of FIG. 1.

Referring to FIGS. 1 and 2, the beam steering device BS may include awaveguide 20 provided on a substrate 10, a cladding layer 30 provided onthe waveguide 20, and an electrode layer 40. The beam steering device BSmay further include a driver D that drives the beam steering device BS.

The substrate 10 may be, for example, a silicon substrate. However,exemplary embodiments are not limited thereto, and the substrate 10 mayinclude any of various other materials. The waveguide 20 may be providedon a top surface of the substrate 10.

A beam passing through the waveguide 20 may be totally reflected withinthe waveguide 20. A beam may be incident on one side surface of thewaveguide 20 and may be emitted through the opposite surface of thewaveguide 20. The beam may be a laser beam or a beam emitted from alight-emitting device. The beam incident on the waveguide 20 is denotedby LI and the beam emitted from the waveguide 20 is denoted by LO. Thewaveguide 20 may include, for example, silicon or silicon nitride.However, exemplary embodiments are not limited thereto, and thewaveguide 20 may be formed of a material whose refractive index ishigher than that of the cladding layer 30.

The cladding layer 30 may include a material whose refractive indexvaries according to an electrical signal applied to the cladding layer30. The cladding layer 30 may include an electro-optic material. Forexample, the cladding layer 30 may include a liquid crystal, TiN,KTa_(1-x)Nb_(x)O₃ (KTN), or NbO_(x).

The cladding layer 30 may include, for example, an oxide semiconductor.The cladding layer 30 may include a transparent conductive oxide (TCO)whose refractive index varies according to an electrical signal appliedto the cladding layer 30. The TCO may include at least one from among,for example, Indium-Tin-Oxide (ITO), Indium-Zinc-Oxide (IZO),Ga—In—Zn-Oxide (GIZO), Al—Zn-Oxide (AZO), Ga—Zn-Oxide (GZO), and ZnO,although exemplary embodiments are not limited thereto. The claddinglayer 30 may have a p-n junction structure along with the waveguide 20.

The electrode layer 40 may be provided on the cladding layer 30. Theelectrode layer 40 may function as an electrode for applying a voltageto the cladding layer 30 and may include at least two electrodes thatmay be independently driven. For example, the electrode layer 40 mayinclude a first electrode 41 and a second electrode 42 that are separatefrom each other. The electrode layer 40 may include at least oneselected from the group consisting of, for example, titanium (Ti), gold(Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), nickel(Ni), and chromium (Cr). However, exemplary embodiments are not limitedthereto, and the electrode layer 40 may include, for example, heavilydoped n++ Si or low resistance ITO. The waveguide 20 may operate as acommon electrode of the first electrode 41 and the second electrode 42.

The first electrode 41 and the second electrode 42 may be provided invarious ways. For example, surfaces of the first electrode 41 and thesecond electrode 42 facing each other may be inclined as shown in FIG.2. The first electrode 41 and the second electrode 42 may be separatefrom each other, and an insulating material may be further providedbetween the first electrode 41 and the second electrode 42. Also,although the electrode layer 40 of the beam steering device BS of FIGS.1 and 2 is exemplarily shown as including two electrodes, the electrodelayer 40 may include three or more electrodes.

When a voltage is applied to the cladding layer 30, a carrier density inthe cladding layer 30 at an interface between the cladding layer 30 andthe waveguide 20 is changed and thus a refractive index of the claddinglayer 30 is changed. Once the refractive index of the cladding layer 30is changed, the waveguide 20 adjacent to the cladding layer 30 isaffected and an effective refractive index of the waveguide 20 is alsochanged, which will be explained below.

Examples of a method of changing a refractive index of a waveguideinclude a method using heat and a method using electricity. In themethod using heat, although a phase change is large and the waveguidemay be formed of any of various materials, a speed is low, waveguideshave to be spaced apart by a predetermined interval or more due tosevere interference between the waveguides, and it is difficult toachieve a wide field of view (FOV). Also, in the method usingelectricity, although a speed is high and a wide FOV is achieved due tono interference between waveguides, a long waveguide is required due toa small phase change, a waveguide material is limited to a semiconductormaterial such as silicon (Si) due to the use of a p-n or p-i-n junctionstructure, and it is difficult to steer laser beams of variouswavelengths.

In contrast, the beam steering device BS of the present exemplaryembodiment may change an effective refractive index of the waveguide 20by using the cladding layer 30 whose refractive index varies accordingto an electrical signal applied to the cladding layer 30 around thewaveguide 20. In the present exemplary embodiment, a beam passingthrough the waveguide 20 may respond to a change in a refractive indexby changing a refractive index of the cladding layer 30 provided aroundthe waveguide 20 without changing a refractive index of the waveguide 20itself. Accordingly, since a refractive index of the waveguide 20 itselfis not changed, beam loss may be small. Also, since any of variousmaterials such as silicon or silicon nitride is used as a material ofthe waveguide 20, beams of various wavelengths may be steered. Also,since an electrical signal, instead of heat, is used, a speed may behigh and a wide FOV may be achieved.

FIG. 3A is a graph showing a relationship between a wavelength and aneffective refractive index n_(eff) of the waveguide 20 when a laser beampasses through the beam steering device BS of FIG. 1 (in a TM0 mode).The term ‘TM mode’ refers to a transverse magnetic mode of anelectromagnetic field in a waveguide when a magnetic field is formed ina direction perpendicular to a propagation direction of anelectromagnetic wave. The TM0 mode is a TM mode whose mode number is 0.

FIG. 3B is a graph showing a relationship between a wavelength and aneffective refractive index n_(eff) of the waveguide 20 when a laser beampasses through the beam steering device BS of FIG. 1 (in a TE0 mode).The term ‘TE mode’ refers to a transverse electric mode of anelectromagnetic field in a waveguide when an electric field is formed ina direction perpendicular to a propagation direction of anelectromagnetic wave. The TE0 mode is a TE mode whose mode number is 0.

In FIGS. 3A and 3B, the waveguide 20 was formed of silicon and thecladding layer 30 was formed of ITO. The term ‘effective refractiveindex n_(eff)’ refers to a refractive index of the waveguide 20 sensedby a laser beam passing through the waveguide 20 when a voltage wasapplied to the cladding layer 30 and a refractive index of the claddinglayer 30 was changed whereas a refractive index of the waveguide 20 wasnot changed. “A” indicates a case where a voltage was not applied to thecladding layer 30 and “B” indicates a case where a voltage of 4 V wasapplied to the cladding layer 30.

Referring to FIGS. 3A and 3B, an effective refractive index changeΔn_(eff) at a wavelength of 1100 nm was about 0.033 in the TM0 mode andwas about 0.0122 in the TE0 mode. The term ‘effective refractive indexchange Δn_(eff)’ refers to a difference between an effective refractiveindex of the waveguide 20 when a voltage was not applied to the claddinglayer 30 and an effective refractive index of the waveguide 20 when avoltage of 4 V was applied to the cladding layer 30. As such, aneffective refractive index of the waveguide 20 may be changed accordingto a voltage applied to the cladding layer 30. When different voltagesare applied to the first electrode 41 and the second electrode 42, aportion of the cladding layer 30 corresponding to the first electrode 41and a portion of the cladding layer 30 corresponding to the secondelectrode 42 may have different refractive indices. Effective refractiveindices of the waveguide 20 corresponding to the portions of thecladding layer 30 may be changed according to the different refractiveindices. Hence, when a beam passes through two portions having differenteffective refractive indices of the waveguide 20, the beam may berefracted and a propagation path of the beam may be changed. Arefraction angle of a beam passing through the waveguide 20 may bechanged according to a difference between voltages respectively appliedto the first electrode 41 and the second electrode 42, and thus the beammay be steered. Since the waveguide 20 functions as a common electrodein the beam steering device BS of FIG. 1, a first voltage may be appliedbetween the waveguide 20 and the first electrode 41 and a second voltagemay be applied between the waveguide 20 and the second electrode 42.

For example, directions of a first output beam LO1 and a second outputbeam LO2 may vary according to a difference between the first voltageand the second voltage as shown in FIG. 2.

FIG. 4 is a cross-sectional view of a beam steering device BS1 accordingto another exemplary embodiment. The beam steering device BS1 isdifferent from the beam steering device BS of FIG. 1 in that anelectrode 15 is further provided. The beam steering device BS of FIG. 1is configured so that the waveguide 20 functions as an electrode whereasthe beam steering device BS1 includes the electrode 15 between thesubstrate 10 and the waveguide 20. The electrode 15 may include at leastone selected from the group consisting of, for example, Ti, Au, Ag, Pt,Cu, Al, Ni, and Cr.

FIG. 5 is a cross-sectional view of a beam steering device BS2 accordingto another exemplary embodiment. The beam steering device BS2 mayinclude a waveguide 120 provided on a substrate 110, a cladding layer130 provided on the waveguide 120, and an electrode layer 140.

The substrate 110 may be, for example, a silicon substrate. However,exemplary embodiments are not limited thereto, and the substrate 110 mayinclude any of various other materials. The waveguide 120 may beprovided on a top surface of the substrate 110.

A beam passing through the waveguide 120 may be totally reflected withinthe waveguide 120. The waveguide 120 may include, for example, siliconor silicon nitride. However, exemplary embodiments are not limitedthereto, and the waveguide 120 may be formed of a material whoserefractive index is higher than that of the cladding layer 130.

The cladding layer 130 may include a first layer 131 and a second layer132. The first layer 131 may include at least one from among ITO, IZO,GIZO, AZO, GZO, and ZnO. The second layer 132 may include at least onefrom among HfO₂, Al₂O₃, SiN_(x), and SiO₂. A refractive index of thefirst layer 131 may vary according to an electrical signal applied tothe first layer 131. The cladding layer 130 may have a metal oxidesemiconductor (MOS) structure along with the electrode layer 140.

The electrode layer 140 may include a first electrode 141 and a secondelectrode 142. Each of the first electrode 141 and the second electrode142 may include at least one selected from the group consisting of Ti,Au, Ag, Pt, Cu, Al, Ni, and Cr. However, exemplary embodiments are notlimited thereto, and each of the first electrode 141 and the secondelectrode 142 may include, for example, heavily doped n++ Si or lowresistance ITO. The waveguide 120 may operate as a common electrode ofthe first electrode 141 and the second electrode 142. The firstelectrode 141 and the second electrode 142 may be provided in variousways as long as the first electrode 141 and the second electrode 142 areelectrically independently driven. For example, the first electrode 141and the second electrode 142 may be physically separate from each other,or may be provided in other ways.

When different voltages are applied to the first electrode 141 and thesecond electrode 142, a portion of the cladding layer 130 correspondingto the first electrode 141 and a portion of the cladding layer 130corresponding to the second electrode 142 may have different refractiveindices. Effective refractive indices of the waveguide 120 correspondingto the portions of the cladding layer 130 may be changed according tothe different refractive indices. Hence, when a beam passes through twoportions having different effective refractive indices of the waveguide120, the beam may be refracted and a propagation of the beam may bechanged. A refraction angle of a beam passing through the waveguide 120may be changed according to a difference between voltages respectivelyapplied to the first electrode 141 and the second electrode 142 and thusthe beam may be steered. Since the waveguide 120 functions as a commonelectrode in the beam steering device BS2, a first voltage may beapplied between the waveguide 120 and the first electrode 141 and asecond voltage may be applied between the waveguide 120 and the secondelectrode 142. Directions of a beam LO output through the waveguide 120may vary according to a difference between the first voltage and thesecond voltage.

FIG. 6 is a cross-sectional view of a beam steering device BS3 accordingto another exemplary embodiment. FIG. 7 is a plan view of the beamsteering device BS3 of FIG. 6.

The beam steering device BS3 may include a waveguide 220 provided on asubstrate 210, a cladding layer 230 and an electrode layer 240 providedon the waveguide 220.

The substrate 210 may be, for example, a silicon substrate. However,exemplary embodiments are not limited thereto, and the substrate 210 mayinclude any of various other materials. The waveguide 220 may beprovided on a top surface of the substrate 210.

A beam passing through the waveguide 220 may be totally reflected withinthe waveguide 220. The waveguide 220 may include, for example, siliconor silicon nitride. The cladding layer 230 may include a material whoserefractive index varies according to an electrical signal applied to thecladding layer 230. The cladding layer 230 may include an electro-opticmaterial. For example, the cladding layer 230 may include a liquidcrystal, TiN, KTN, or NbO_(x).

Alternatively, the cladding layer 230 may include an oxidesemiconductor. The cladding layer 230 may include a TCO whose refractiveindex varies according to an electrical signal applied to the claddinglayer 230. The TCO may include at least one from among, for example,ITO, IZO, GIZO, AZO, GZO, and ZnO. The cladding layer 230 may have a p-njunction structure along the waveguide 220. Alternatively, the claddinglayer 230 may have a metal oxide semiconductor structure along theelectrode layer 240. The metal oxide semiconductor structure may be thesame as that described with reference to FIG. 5, and thus a detailedexplanation thereof will not be given.

The electrode layer 240 may include a plurality of pixel electrodes PEthat are arranged in a matrix to be electrically independent. Aninsulating material 245 may be provided between the pixel electrodes PE.The electrode layer 240 may include at least one selected from the groupconsisting of Ti, Au, Ag, Pt, Cu, Al, Ni, and Cr. However, exemplaryembodiments are not limited thereto, and the electrode layer 240 mayinclude, for example, heavily doped n++ Si or low resistance ITO. Thewaveguide 220 may operate as a common electrode. Alternatively, aseparate common electrode may be additionally provided.

The pixel electrodes PE may be independently driven. For example, theelectrode layer 240 may be divided into a first portion A11 and a secondportion A12, and a first voltage may be applied to the pixel electrodesPE in the first portion A11 and a second voltage may be applied to thepixel electrodes PE in the second portion A12. In FIG. 7, a boundarybetween the first portion A11 and the second portion A12 has a steppedshape ST according to shapes of the pixel electrodes PE. However, FIG. 7is an exaggerated illustration of certain features, and since the pixelelectrodes PE are actually very small, a boundary between the firstportion A11 and the second portion A12 may be substantially a linearline Li.

When the first voltage is applied to the pixel electrodes PE in thefirst portion A11, a portion of the cladding layer 230 corresponding tothe first portion A11 may have a first refractive index, and when thesecond voltage is applied to the pixel electrodes PE in the secondportion A12, a portion of the cladding layer 230 corresponding to thesecond portion A12 may have a second refractive index. An effectiverefractive index difference occurs in the waveguide 220 according to adifference between the first refractive index and the second refractiveindex, and a refraction angle of a beam passing through the waveguide220 may be controlled according to the effective refractive indexdifference, thereby making it possible to control a direction in whichthe beam is output.

FIG. 8 is a plan view illustrating an example where a first portion A21to which a first voltage is applied and a second portion A22 to which asecond voltage is applied are changed. A gradient of a boundary betweenthe first portion A21 and the second portion A22 is different from thatin FIG. 7. Portions to which the first voltage and the second voltageare applied may be changed by selectively driving the plurality of pixelelectrodes PE. Hence, a refraction direction of a beam passing throughthe waveguide 220 may be controlled. For example, a beam LO1 outputthrough the waveguide 220 in FIG. 7 may be more refracted and outputthan a beam LO2 output through the waveguide 220 in FIG. 8.

In FIG. 7, a refractive index of a cladding portion corresponding to thefirst portion A11 and a refractive index of a cladding portioncorresponding to the second portion A12 may be changed by changing avoltage applied to the pixel electrodes PE in the first portion A11 anda voltage applied to the pixel electrodes PE in the second portion A12while maintaining the first portion A11 and the second portion A12.Accordingly, a beam may be steered due to a difference between therefractive indices.

In FIG. 7, a beam may be steered by adjusting a direction which the beamis output by adjusting at least one from among a first voltage, a secondvoltage, a portion to which the first voltage is applied, and a portionto which the second voltage is applied.

FIG. 9 is a graph showing a relationship between an angle α at which abeam is output and a gradient θ of a boundary between the first portionA11 and the second portion A12 of the electrode layer 240. The angle αrefers to a gradient of an emitted beam with respect to a normal line ofan emission surface of the waveguide 220. As shown in FIG. 9, the angleα may be adjusted according to the gradient θ of the boundary betweenthe first portion A11 and the second portion A12 of the electrode layer240.

FIG. 10 is a cross-sectional view of a beam steering device BS4according to another exemplary embodiment. The beam steering device BS4may have a stacked structure including a first waveguide 320 provided ona first substrate 310, a first cladding layer 330 provided on the firstwaveguide 320, and a first electrode layer 340, and the stackedstructure may be repeatedly stacked two or more times.

For example, a second substrate 350, a second waveguide 360, a secondcladding layer 370, and a second electrode layer 380 may be stacked onthe first electrode layer 340. Also, the second waveguide 360 may bedirectly stacked on the first electrode layer 340 without the secondsubstrate 350 therebetween.

The first electrode layer 340 may include at least two electrodes, andthe second electrode layer 380 may include at least two electrodes. Thefirst electrode layer 340 may include, for example, a first electrode341 and a second electrode 342. An insulating material 343 may beprovided between the first electrode 341 and the second electrode 342.The second electrode layer 380 may include a third electrode 381 and afourth electrode 382. An insulating material 383 may be provided betweenthe third electrode 381 and the fourth electrode 382. Alternatively, thefirst electrode layer 340 may include a plurality of pixel electrodesand the second electrode layer 380 may include a plurality of pixelelectrodes.

In the present exemplary embodiment, beam steering may be performed atdifferent heights by using a stacked structure. A first incident beamLI1 may be output as a first emitted beam LO1 through the firstwaveguide 320, and the first emitted beam LO1 may be steered in adirection perpendicular to the ground due to a difference betweenvoltages respectively applied to the first electrode 341 and the secondelectrode 342. A second incident beam LI2 may be output as a secondemitted beam LO2 through the second waveguide 360, and the secondemitted beam LO2 may be steered in a direction perpendicular to theground due to a difference between voltages respectively applied to thethird electrode 381 and the fourth electrode 382. The first emitted beamLO1 and the second emitted beam LO2 are emitted at different heights.Hence, beams may be steered in various directions at various heights byusing a stacked structure.

As described in the above exemplary embodiments, a beam steering devicemay include a cladding layer whose refractive index varies according toan electrical signal and at least two independent electrodes that mayemit different voltages so that a waveguide operates as an active prism.Accordingly, the beam steering device may simply steer a beam by usingan electrical control method.

In the above exemplary embodiments, since a refractive index of awaveguide itself is not changed, beam loss may be small. Since variousmaterials such as silicon or silicon nitride may be used as a materialof the waveguide, laser beams of various wavelengths may be steered.Also, since an electrical signal, instead of heat, is used, a beamsteering speed may be high and a wide FOV may be achieved. Also, since alight transmission method, instead of an OPA method, is used, lightefficiency may be high.

FIG. 11 is a view of a system 400 according to an exemplary embodiment.FIG. 11 illustrates the system 400 using a beam steering device 420according to an exemplary embodiment.

Referring to FIG. 11, the system 400 according to an exemplaryembodiment may include a light source 410 that emits a beam, the beamsteering device 420 that steers a beam, a detector 440 that detects abeam reflected by an object O, and a driver 430. The driver 430 mayinclude a driving circuit for driving the light source 410, the beamsteering device 420, and the detector 440.

The light source 410 may be, for example, a laser diode or alight-emitting device. However, exemplary embodiments are not limitedthereto, and the light source 410 may be any of various other lightsources. A beam emitted from the light source 410 is incident on thebeam steering device 420. The beam steering device 420 may steer theincident beam to a desired position. Examples of the beam steeringdevice 420 may include the beam steering devices BS, BS1, BS2, BS3, andBS4 according to the above various exemplary embodiments, or anycombination thereof. The beam steered by the beam steering device 420may be emitted to and reflected by the object O, and the detector 440may detect the reflected beam. Various examples of the system 400 towhich the beam steering device 420 may be applied include a depthsensor, a three-dimensional (3D) sensor, and a light detection andranging (LiDAR). Beams may be steered in a horizontal direction and avertical direction of the object O by using the beam steering device BS4having a stacked structure as shown in FIG. 10. Accordingly, a 3D imageof the object O may be obtained.

While exemplary embodiments have been described with reference to thefigures, it will be understood by one of ordinary skill in the art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope as defined by the following claims.

What is claimed is:
 1. A beam steering device comprising: a waveguideconfigured to transmit a beam therethrough; a cladding layer provided onthe waveguide and comprising a material having a refractive index thatvaries according to a voltage applied thereto; and an electrode layercomprising at least two electrodes configured to independently applyvoltages to at least two portions of the cladding layer.
 2. The beamsteering device of claim 1, wherein the at least two electrodes areelectrically independent.
 3. The beam steering device of claim 1,wherein the cladding layer comprises an electro-optic material.
 4. Thebeam steering device of claim 3, wherein the electro-optic materialcomprises a liquid crystal, TiN, KTa_(1-x)Nb_(x)O₃ (KTN), or NbO_(x). 5.The beam steering device of claim 1, wherein the cladding layercomprises an oxide semiconductor.
 6. The beam steering device of claim5, wherein the oxide semiconductor comprises at least one from amongIndium-Tin-Oxide (ITO), Indium-Zinc-Oxide (IZO), Ga—In—Zn-Oxide (GIZO),Al—Zn-Oxide (AZO), Ga—Zn-Oxide (GZO), and ZnO.
 7. The beam steeringdevice of claim 1, wherein the waveguide comprises silicon or siliconnitride.
 8. The beam steering device of claim 1, wherein the waveguideis configured to operate as an electrode.
 9. The beam steering device ofclaim 1, wherein the at least two electrodes of the electrode layercomprise a plurality of pixel electrodes that are arranged in a matrixand are electrically independent.
 10. The beam steering device of claim1, wherein the electrode layer comprises a first portion configured toapply a first voltage to a first portion the cladding layer and a secondportion configured to apply a second voltage to a second portion of thecladding layer.
 11. The beam steering device of claim 1, wherein thecladding layer comprises a metal oxide semiconductor structure providedalong a surface of the electrode layer.
 12. The beam steering device ofclaim 11, wherein the cladding layer comprises a first layer and asecond layer, wherein the first layer comprises at least one from amongIndium-Tin-Oxide (ITO), Indium-Zinc-Oxide (IZO), Ga—In—Zn-Oxide (GIZO),Al—Zn-Oxide (AZO), Ga—Zn-Oxide (GZO), and ZnO and the second layercomprises any one from among HfO₂, Al₂O₃, SiN_(x), and SiO₂.
 13. Thebeam steering device of claim 1, wherein the waveguide, the claddinglayer, and the electrode layer are repeatedly stacked at least twotimes.
 14. The beam steering device of claim 1, wherein the waveguide isconfigured to operate as an active prism according to a change in therefractive index of the cladding layer.
 15. A system comprising: a lightsource; a beam steering device configured to steer a beam incident fromthe light source towards an object; and a detector configured to detectthe beam steered by the beam steering device and reflected by theobject, wherein the beam steering device comprises: a waveguideconfigured to transmit the beam therethrough; a cladding layer providedon the waveguide and comprising a material having a refractive indexthat varies according to a voltage applied thereto; and an electrodelayer comprising at least two electrodes configured to independentlyapply voltages to at least two portions of the cladding layer.
 16. Thesystem of claim 15, wherein the cladding layer comprises anelectro-optic material.
 17. The system of claim 16, wherein theelectro-optic material comprises a liquid crystal, TiN,KTa_(1-x)Nb_(x)O₃ (KTN), or NbO_(x).
 18. The system of claim 15, whereinthe cladding layer comprises an oxide semiconductor.
 19. The system ofclaim 15, wherein the at least two electrodes of the electrode layercomprise a plurality of pixel electrodes that are arranged in a matrixand are electrically independent.